Audio amplifier



FIG. 1 is a perspective view of an audio amplifier showing our design;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a left side view thereof.

The broken lines in the figures show portions of the audio amplifier that form no part of the claimed design. 

CLAIM We claim the ornamental design for an audio amplifier, as shown and described. 